Liquid crystal composition and liquid crystal display device

ABSTRACT

A liquid crystal composition is provided that satisfies at least one characteristic among the characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of a nematic phase, a small viscosity, a large optical anisotropy, a large dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or is properly balanced regarding at least two characteristics. An AM device is provided that has a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth. The liquid crystal composition contains a specific tricyclic compound having a large optical anisotropy as the first component and a specific tetracyclic compound having a large dielectric anisotropy as the second component, and may contain a specific bicyclic compound having a particularly small viscosity as the third component. The liquid crystal composition has a nematic phase. The liquid crystal display device contains the liquid crystal composition.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to JapanesePatent Application No. JP 2007-237395, filed Sep. 13, 2007, whichapplication is expressly incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a liquid crystal composition suitable for usein an active matrix (AM) device, and an AM device containing thecomposition. More specifically, the invention relates to a liquidcrystal composition having a positive dielectric anisotropy, and alsorelates to a device of a twisted nematic (TN) mode, an opticallycompensated bend (OCB) mode, an in-plane switching (IPS) mode or apolymer sustained alignment (PSA) mode containing the composition.

2. Related Art

In a liquid crystal display device, classification based on an operatingmode of liquid crystals includes phase change (PC), twisted nematic(TN), super twisted nematic (STN), electrically controlled birefringence(ECB), optically compensated bend (OCB), in-plane switching (IPS),vertical alignment (VA), a polymer sustained alignment (PSA) mode and soforth. Classification based on a driving mode of the device includes apassive matrix (PM) and an active matrix (AM). PM is further classifiedinto static, multiplex and so forth, and AM is classified into a thinfilm transistor (TFT), a metal insulator metal (MIM) and so forth. TFTis further classified into amorphous silicon and polycrystal silicon.The latter is classified into a high temperature type and a lowtemperature type according to a production process. Classification basedon a light source includes a reflection type utilizing a natural light,a transmission type utilizing a backlight and a semi-transmission typeutilizing both the natural light and the backlight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to obtainan AM device having good general characteristics. Table 1 belowsummarizes a relationship between the general characteristics of thetwo. The general characteristics of the composition will be explainedfurther based on a commercially available AM device. A temperature rangeof a nematic phase relates to the temperature range in which the devicecan be used. A desirable maximum temperature of the nematic phase isapproximately 70° C. or more and a desirable minimum temperature thereofis approximately −10° C. or less. The viscosity of the compositionrelates to the response time of the device. The rotation viscosity is inthe same situation as the viscosity. A short response time is desirablefor displaying a moving image with the device. Accordingly, a smallviscosity of the composition is desirable. A small viscosity at a lowtemperature is more desirable.

TABLE 1 General Characteristics of Liquid Crystal Composition and AMDevice General Characteristics General Characteristics No of aComposition of an AM Device 1 Temperature range of a Usable temperaturerange nematic phase is wide is wide 2 Viscosity is small¹⁾ Response timeis short 3 Optical anisotropy is suitable Contrast ratio is large 4Dielectric anisotropy is Threshold voltage is low, positively ornegatively large electric power consumption is small and contrast ratiois large 5 Specific resistance is large Voltage holding ratio is largeand a contrast ratio is large 6 It is stable to ultraviolet Service lifeis long light and heat ¹⁾A liquid crystal composition can be injectedinto a cell in a short time.

The optical anisotropy of the composition relates to the contrast ratioof the device. A product (Δn·d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed to maximizethe contrast ratio. A suitable value of the product depends on the kindof operation mode. In a device having such a mode as a TN mode, asuitable value is approximately 0.45 μm. In this case, a compositionhaving a large optical anisotropy is desirable for a device having asmall cell gap. A large dielectric anisotropy of the compositioncontributes to a low threshold voltage, a small electric powerconsumption and a large contrast ratio of the device. Accordingly, alarge dielectric anisotropy is desirable. A large specific resistance ofthe composition contributes to a large voltage holding ratio and a largecontrast ratio of the device. Accordingly, a composition having a largespecific resistance is desirable at room temperature and also at a hightemperature in the initial stage. A composition having a large specificresistance is desirable at room temperature and also at a hightemperature after it has been used for a long time. A stability of thecomposition to an ultraviolet light and heat relates to a service lifeof the liquid crystal display device. In the case where the stability ishigh, the device has a long service life. These characteristics aredesirable for an AM device used in a liquid crystal projector, a liquidcrystal television and so forth.

In an AM device having a TN mode, a composition having a positivedielectric anisotropy is used. In an AM device having a VA mode, acomposition having a negative dielectric anisotropy is used. In an AMdevice having an IPS mode, a composition having a positive or negativedielectric anisotropy is used. In an AM device having a PSA mode, acomposition having a positive or negative dielectric anisotropy is used.A liquid crystal composition having a negative dielectric anisotropy isdisclosed in the following document. Conventional compounds andcompositions are disclosed in JP H9-278684 A/1997, JP H9-286742 A/1997and JP H9-328443 A/1997 and JP H10-81881 A/1998.

A desirable AM device is characterized as having a usable temperaturerange that is wide, a response time that is short, a contrast ratio thatis large, a threshold voltage that is low, a voltage holding ratio thatis large, a service life that is long, and so forth. Even onemillisecond shorter response time is desirable. Thus, the compositionhaving characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of a nematic phase, a small viscosity,a large optical anisotropy, a large dielectric anisotropy, a largespecific resistance, a high stability to an ultraviolet light, a highstability to heat, and so forth is especially desirable.

SUMMARY OF THE INVENTION

The invention concerns a liquid crystal composition having a nematicphase that includes two components, wherein the first component is acompound represented by formula (1), and the second component is atleast one compound selected from the group consisting of compoundsrepresented by formula (2):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; X¹, X², X³and X⁴ are each independently hydrogen or fluorine; and Y¹ is fluorine,chlorine or trifluoromethoxy.

The invention also concerns a liquid crystal display device thatincludes the liquid crystal composition, and so forth.

DETAILED DESCRIPTION OF THE INVENTION

The terms used in the specification and claims are defined as follows.The liquid crystal composition and/or the liquid crystal display deviceof the invention may occasionally be expressed simply as “thecomposition” or “the device,” respectively. A liquid crystal displaydevice is a generic term for a liquid crystal display panel and a liquidcrystal display module. The “liquid crystal compound” is a generic termfor a compound having a liquid crystal phase such as a nematic phase, asmectic phase and so forth, and also for a compound having no liquidcrystal phase but being useful as a component of a composition. Theuseful compound contains, for example, a 6-membered ring such as1,4-cyclohexylene and 1,4-phenylene, and a rod like molecular structure.An optically active compound or a polymerizable compound mayoccasionally be added to the composition. Even in the case where thecompound is a liquid crystal compound, the compound is classified intoan additive. At least one compound selected from a group consisting ofcompounds represented by formula (1) may be abbreviated to “the compound(1).” The “compound (1)” means one compound or two or more compoundsrepresented by formula (1). The other formulas are applied with the samerules. The term “arbitrary” means that not only the position but alsothe number are arbitrary, but the case where the number is zero is notincluded.

A higher limit of a temperature range of a nematic phase may beabbreviated to “a maximum temperature.” A lower limit of a temperaturerange of a nematic phase may be abbreviated to “a minimum temperature.”“A specific resistance is large” means that the composition has a largespecific resistance at room temperature and also at a high temperaturein the initial stage; the composition has a large specific resistance atroom temperature and also at a high temperature even after it has beenused for a long time. “A voltage holding ratio is large” means that adevice has a large voltage holding ratio at room temperature and also ata high temperature in the initial stage, the device has a large voltageholding ratio at room temperature and also at a high temperature evenafter it has been used for a long time. In the description of thecharacteristics such as optical anisotropy, the characteristics of thecomposition such as the optical anisotropy and so forth are valuesmeasured in the methods disclosed in Examples. The first componentincludes one compound or two or more compounds. “A content ratio of thefirst component” means the percentage by weight (% by weight) of thefirst component based on the total weight of liquid crystal composition.A content ratio of the second component and so forth are applied withthe same rule. A ratio of an additive mixed with the composition meansthe percentage by weight (% by weight) based on the total weight ofliquid crystal composition.

In the chemical formulas of the component compounds, symbol R¹ is usedin plural compounds. In these compounds, plural R¹ may be the same as ordifferent from each other. In one case, for example, R¹ of the compound(2) is ethyl and R¹ of the compound (3-1) is ethyl.

In another case, R¹ of the compound (2) is ethyl and R¹ of the compound(3-1) is propyl. This rule is also applicable to the symbols R², R³ andso forth.

One of the advantages of the invention is to provide a liquid crystalcomposition that satisfies many characteristics among thecharacteristics such as a high maximum temperature of a nematic phase, alow minimum temperature of a nematic phase, a small viscosity, a largeoptical anisotropy, a large dielectric anisotropy, a large specificresistance, a high stability to ultraviolet light and a high stabilityto heat. Another of the advantages of the invention is to provide aliquid crystal composition that is properly balanced regarding manycharacteristics. Another of the advantages of the invention is toprovide a liquid crystal display device that contains the liquid crystalcomposition. One aspect of the invention is to provide a liquid crystalcomposition that has a large optical anisotropy, a large dielectricanisotropy, a high stability to ultraviolet light and so forth, and isto provide an AM device that has a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth.

The invention has the following features.

1. A liquid crystal composition having a nematic phase comprising twocomponents, wherein the first component is a compound represented byformula (1), and the second component is at least one compound selectedfrom the group consisting of compounds represented by formula (2):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; X¹, X², X³and X⁴ are each independently hydrogen or fluorine; and Y¹ is fluorine,chlorine or trifluoromethoxy.

2. The liquid crystal composition according to item 1, wherein thesecond component is at least one compound selected from the groupconsisting of compounds represented by formulas (2-1) to (2-3):

wherein R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons.

3. The liquid crystal composition according to item 2, wherein thesecond component is at least one compound selected from the groupconsisting of compounds represented by formula (2-1).

4. The liquid crystal composition according to any one of items 1 to 3,wherein a content ratio of the first component is from approximately 5%by weight to approximately 30% by weight, and a content ratio of thesecond component is from approximately 5% by weight to approximately 30%by weight, based on the total weight of the liquid crystal composition.

5. The liquid crystal composition according to any one of items 1 to 4,wherein the composition further comprises at least one compound selectedfrom the group consisting of compounds represented by formulas (3-1) to(3-3) as a third component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; and ring B, ring C, ring D, ring E, ring F and ring G are eachindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneor 3-fluoro-1,4-phenylene.

6. The liquid crystal composition according to item 5, wherein the thirdcomponent is at least one compound selected from the group consisting ofcompounds represented by formulas (3-1-1), (3-1-2), (3-2-1) to (3-2-4)and (3-3-1) to (3-3-3):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; and R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to12 carbons.

7. The liquid crystal composition according to item 6, wherein the thirdcomponent is at least one compound selected from the group consisting ofcompounds represented by formula (3-1-1).

8. The liquid crystal composition according to item 6, wherein the thirdcomponent is at least one compound selected from the group consisting ofcompounds represented by formula (3-2-1).

9. The liquid crystal composition according to item 6, wherein the thirdcomponent is at least one compound selected from the group consisting ofcompounds represented by formula (3-2-3).

10. The liquid crystal composition according to item 6, wherein thethird component is at least one compound selected from the groupconsisting of compounds represented by formula (3-3-3).

11. The liquid crystal composition according to any one of items 5 to10, wherein a content ratio of the third component is from approximately40% by weight to approximately 95% by weight based on the total weightof the liquid crystal composition.

12. The liquid crystal composition according to any one of items 1 to11, wherein the composition further comprises at least one compoundselected from the group consisting of compounds represented by formula(4) as a fourth component:

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; ring A isindependently 1,4-cyclohexylene, 1,3-dioxan-2,5-diyl, 1,4-phenylene,3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene or 2,5-pirimidine; Z¹is independently a single bond, ethylene, carbonyloxy ordifluoromethyleneoxy; X¹ and X² are each independently hydrogen orfluorine; Y¹ is fluorine, chlorine or trifluoromethoxy; and n is 1 or 2.

13. The liquid crystal composition according to item 12, wherein thefourth component is at least one compound selected from the groupconsisting of compounds represented by formulas (4-1) to (4-12):

wherein R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons.

14. The liquid crystal composition according to item 13, wherein thefourth component is at least one compound selected from the groupconsisting of compounds represented by formula (4-6).

15. The liquid crystal composition according to item 13, wherein thefourth component is at least one compound selected from the groupconsisting of compounds represented by formula (4-8).

16. The liquid crystal composition according to item 13, wherein thefourth component is at least one compound selected from the groupconsisting of compounds represented by formula (4-10).

17. The liquid crystal composition according to item 13, wherein thefourth component is at least one compound selected from the groupconsisting of compounds represented by formula (4-11).

18. The liquid crystal composition according to item 13, wherein thefourth component is a mixture of at least one compound selected from thegroup consisting of compounds represented by formula (4-6) and at leastone compound selected from the group consisting of compounds representedby formula (4-11).

19. The liquid crystal composition according to any one of items 12 to18, wherein a content ratio of the fourth component is fromapproximately 5% by weight to approximately 35% by weight based on thetotal weight of the liquid crystal composition.

20. The liquid crystal composition according to any one of items 1 to19, wherein the composition has a maximum temperature of a nematic phaseof approximately 70° C. or more, an optical anisotropy (25° C.) at awavelength of 589 nm of approximately 0.08 or more, and a dielectricanisotropy (25° C.) at a frequency of 1 kHz of approximately 2 or more.

21. A liquid crystal display device that includes the liquid crystalcomposition according to any one of items 1 to 20.

22. The liquid crystal display device according to item 21, wherein theliquid crystal display device has an operation mode of a TN mode, an OCBmode, an IPS mode or a PSA mode, and has a driving mode of an activematrix mode.

The invention further includes: (1) the composition described above,wherein the composition further contains an optically active compound;(2) the composition described above, wherein the composition furthercontains an additive, such as an antioxidant, an ultraviolet lightabsorbent, an antifoaming agent, a polymerizable compound and/or apolymerization initiator; (3) an AM device containing the compositiondescribed above; (4) a device having a TN, ECB, OCB, IPS or PSA mode,containing the composition described above; (5) a device of atransmission type, containing the composition described above; (6) useof the composition described above as a composition having a nematicphase; and (7) use as an optically active composition by adding anoptically active compound to the composition described above.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, the main characteristics of the componentcompounds and the main effects of the compounds on the composition willbe explained. Third, combinations of components in the composition,desirable ratios of the component compounds and the basis thereof willbe explained. Fourth, a desirable embodiment of the component compoundswill be explained. Fifth, examples of the component compound will beshown. Sixth, additives that may be added to the composition will beexplained. Seventh, the preparation methods of the component compoundwill be explained. Lastly, use of the composition will be explained.

First, the constitution of component compounds in the composition willbe explained. The composition of the invention is classified into thecomposition A and the composition B. The composition A may furthercontain other compounds such as another liquid crystal compound, anadditive, an impurity, and so forth. This liquid crystal compound isdifferent from the compound (1), the compound (2), the compound (3-1),the compound (3-2), the compound (3-3) and the compound (4). Such aliquid crystal compound is mixed with the composition for the purpose ofadjusting the characteristics of the composition. Among the liquidcrystal compounds, an amount of a cyano compound is desirably small fromthe viewpoint of stability to heat or ultraviolet light. The amount of acyano compound is more desirably approximately 0% by weight. Theadditive includes an optically active compound, an antioxidant, anultraviolet light absorbent, a coloring matter, an antifoaming agent, apolymerizable compound, a polymerization initiator and so forth. Theimpurity is a compound and so forth contaminated in the process such asthe synthesis of a component compound and so forth. This compound isclassified into an impurity even when the compound is a liquid crystalcompound.

The composition B essentially consists of the compounds selected fromthe compound (1), the compound (2), the compound (3-1), the compound(3-2), the compound (3-3) and the compound (4). The term “essentially”means that the composition does not contain a liquid crystal compoundwhich is different from these compounds. The term “essentially” alsomeans that the composition may further contain the additive, theimpurity, and so forth. The components of the composition B are fewerthan those of the composition A. The composition B is preferable to thecomposition A from the viewpoint of decreasing costs. The composition Ais preferable to the composition B, because characteristics of thecomposition A can be further adjusted by mixing with other liquidcrystal compounds.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the composition will be explained. The maincharacteristics of the component compounds are summarized in Table 2. InTable 2, the symbol L represents large or high, the symbol M representsa middle degree, and the symbol S represents small or low. The symbolsL, M and S are classification based on qualitative comparison among thecomponent compounds.

TABLE 2 Characteristics of Compounds Compound (1) (2) (3-1) (3-2) (3-3)(4) Maximum S M S M-L L S-M temperature Viscosity S L S M L S-M OpticalL L S M-L L M-L anisotropy Dielectric 0 L 0 0 0 M-L anisotropy SpecificL L L L L L resistance

The main effects of the component compounds to the characteristics ofthe composition upon mixing the component compounds to the compositionare as follows. The compound (1) increases the optical anisotropy anddecreases the viscosity. The compound (2) increases the opticalanisotropy and increases the dielectric anisotropy. The compound (3-1)decreases the viscosity and decreases the minimum temperature. Thecompound (3-2) increases the optical anisotropy. The compound (3-3)increases the maximum temperature and increases the optical anisotropy.The compound (4) increases the dielectric anisotropy.

Third, combinations of components in the composition, desirable contentratios of the component compounds and the basis therefore will beexplained. Examples of the combinations of the components in thecomposition include (first component+second component), (firstcomponent+second component+third component), (first component+secondcomponent+fourth component) and (first component+second component+thirdcomponent+fourth component). Desirable examples of the combinations ofthe components in the composition include (first component+secondcomponent+third component+fourth component).

A desirable content ratio of the first component is approximately 5% byweight or more for increasing the optical anisotropy, and isapproximately 30% by weight or less for decreasing the minimumtemperature. A more desirable content ratio is from approximately 5% byweight to approximately 20% by weight. A particularly desirable contentratio is from approximately 5% by weight to approximately 15% by weight.

A desirable content ratio of the second component is approximately 5% byweight or more for increasing the dielectric anisotropy, and isapproximately 30% by weight or less for decreasing the viscosity. A moredesirable content ratio is from approximately 5% by weight toapproximately 20% by weight. A particularly desirable content ratio isfrom approximately 5% by weight to approximately 15% by weight.

A desirable content ratio of the third component is approximately 40% byweight or more for decreasing the viscosity, and is approximately 95% byweight or less for decreasing the minimum temperature. A more desirablecontent ratio is from approximately 45% by weight to approximately 85%by weight. A particularly desirable content ratio is from approximately50% by weight to approximately 80% by weight.

A desirable content ratio of the fourth component is approximately 5% byweight or more for increasing the dielectric anisotropy, and isapproximately 35% by weight or less for decreasing the minimumtemperature. A more desirable content ratio is from approximately 5% byweight to approximately 30% by weight. A particularly desirable contentratio is from approximately 5% by weight to approximately 25% by weight.

Fourth, a desirable embodiment of the component compound will beexplained. R¹ and R² are each independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbonsor alkenyl having 2 to 12 carbons in which arbitrary hydrogen isreplaced by fluorine. Desirable R¹ is linear alkyl having 1 to 10carbons in order to enhance the stability to ultraviolet light or heat.Desirable R² is linear alkenyl having 2 to 10 carbons in order todecrease the minimum temperature and to decrease the viscosity. R³ isalkyl having 1 to 12 carbons or alkenyl having 2 to 12 carbons.Desirable R³ is linear alkyl having 1 to 10 carbons in order to enhancethe stability to ultraviolet light or heat.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,or octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl, orheptyl for decreasing a viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy, or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing a viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl, or 3-pentenyl for decreasing aviscosity. A desirable configuration of —CH═CH— in these alkenylsdepends on the position of a double bond. Trans is desirable in thealkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl, and 3-hexenyl for decreasing the viscosity. Cis is desirablein the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thesealkenyls, linear alkenyl is preferable to branched alkenyl.

Preferred examples of alkenyl in which arbitrary hydrogen is replaced byfluorine include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More preferred examples thereof include2,2-difluorovinyl and 4,4-difluoro-3-butenyl for decreasing theviscosity.

Ring A is independently 1,4-cyclohexylene, 1,3-dioxan-2,5-diyl,1,4-phenylene, 3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene or2,5-pirimidine, and in the case where n is 2, two rings A may be thesame or different. Desirable ring A is 1,4-phenylene in order toincrease the optical anisotropy. Ring B, ring C, ring D, ring E, ring Fand ring G are each 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene. Desirable ring B andring C are each 1,4-cyclohexylene in order to in order to decrease theminimum temperature. Desirable ring D and ring F are each3-fluoro-1,4-phenylene in order to decrease the minimum temperature.Desirable ring E and ring G are each 1,4-phenylene in order to increasethe optical anisotropy.

Z¹ is independently a single bond, ethylene, carbonyloxy ordifluoromethyleneoxy, and in the case where n is 2, two bonds or groupsZ¹ may be the same or different. Desirable Z¹ is difluoromethyleneoxy inorder to increase the dielectric anisotropy.

X¹, X², X³ and X⁴ are each independently hydrogen or fluorine. DesirableX¹, X², X³ and X⁴ are two or more fluorines in order to increase thedielectric anisotropy.

Y¹ is fluorine, chlorine or trifluoromethoxy. Desirable Y¹ is fluorinein order to decrease the minimum temperature.

n is 1 or 2. Desirable n is 2 in order to decrease the minimumtemperature.

Fifth, examples of the component compounds will be shown. In thedesirable compounds described below, R⁴ is linear alkyl having 1 to 12carbons. R⁵ is linear alkyl having 1 to 12 carbons or linear alkoxyhaving 1 to 12 carbons. R⁶ and R⁷ are each linear alkyl having 1 to 12carbons or linear alkenyl having 2 to 12 carbons. R⁸ is linear alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine. In these desirable compounds, trans is preferable to cis forthe configuration of 1,4-cyclohexylene for increasing a maximumtemperature.

Desirable compounds (2) are the compounds (2-1-1) to (2-3-1) and (2-4)to (2-8). More desirable compounds (2) are the compounds (2-1-1),(2-2-1) and (2-3-1). Particularly desirable compounds (2) are thecompounds (2-1-1) and (2-3-1). Desirable compounds (3-1) are thecompounds (3-1-1-1) to (3-1-2-1). More desirable compounds (3-1) are thecompounds (3-1-1-1) and (3-1-2-1). Desirable compounds (3-2) are thecompounds (3-2-1-1) to (3-2-4-1). More desirable compounds (3-2) are thecompounds (3-2-1-1) and (3-2-3-1). Desirable compounds (3-3) are thecompounds (3-3-1-1) to (3-3-3-1). Amore desirable compound (3-3) is thecompound (3-3-3-1). Desirable compounds (4) are the compounds (4-1-1) to(4-12-1) and (4-13) to (4-22). More desirable compounds (4) are thecompounds (4-8-1), (4-9-1), (4-11-1) and (4-12-1). Particularlydesirable compounds (4) are the compounds (4-9-1) and (4-11-1).

Sixth, additives capable of being mixed with the composition will beexplained. The additives include an optically active compound, anantioxidant, an ultraviolet light absorbent, a coloring matter, anantifoaming agent, a polymerizable compound, a polymerization initiatorand so forth. An optically active compound is mixed in the compositionfor inducing a helical structure of liquid crystal to provide a twistangle. Examples of the optically active compound include the compounds(5-1) to (5-4) below. A desirable ratio of the optically active compoundis approximately 5% by weight or less, and a more desirable ratiothereof ranges from approximately 0.01% by weight to approximately 2%.

An antioxidant is mixed with the composition in order to avoid adecrease in specific resistance caused by heating in the air, or tomaintain a large voltage holding ratio at room temperature and also at ahigh temperature even after the device has been used for a long time.

Preferred examples of the antioxidant include the compound (6):

wherein n is an integer of from 1 to 9. In the compound (6), desirable nis 1, 3, 5, 7, or 9. More desirable n is 1 or 7. When n is 1, thecompound (6) has a large volatility, and is effective in preventing thedecrease of specific resistance caused by heating in the air. When n is7, the compound (6) has a small volatility, and is effective inmaintaining a large voltage holding ratio at room temperature and alsoat a high temperature even after the device has been used for a longtime. A desirable ratio of the antioxidant is approximately 50 ppm ormore in order to obtain the advantages thereof and is approximately 600ppm or less in order to prevent the maximum temperature from beingdecreased and to prevent the minimum temperature from being increased. Amore desirable ratio is from approximately 100 ppm to approximately 300ppm.

Preferred examples of the ultraviolet light absorbent include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer having steric hindrance such as an amineis also desirable. A desirable ratio of the absorbent and the stabilizeris approximately 50 ppm or more for obtaining the advantages thereof andis approximately 10,000 ppm or less for preventing the maximumtemperature from being decreased and preventing the minimum temperaturefrom being increased. A more desirable ratio thereof ranges fromapproximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition to suit for a device of a guest host (GH) mode. Adesirable ratio of the dye ranges from approximately 0.01% toapproximately 10%. An antifoaming agent such as dimethyl silicone oil ormethylphenyl silicone oil is mixed with the composition for preventingfoaming. A desirable ratio of the antifoaming agent is approximately 1ppm or more for obtaining the advantages thereof and is approximately1,000 ppm or less for preventing display failure from occurring. A moredesirable ratio thereof ranges from approximately 1 ppm to approximately500 ppm.

A polymerizable compound is mixed with the composition for applying thecomposition to a device having a PSA (polymer sustained alignment) mode.Preferred examples of the polymerizable compound include compoundshaving a polymerizable group, such as acrylate, methacrylate, vinyl,vinyloxy, propenyl ether, epoxy and so forth. Particularly preferredexamples thereof include derivatives of acrylate or methacrylate. Adesirable ratio of the polymerizable group is from approximately 0.05%by weight or more for obtaining the advantages thereof, and isapproximately 10% by weight or less for preventing display failure fromoccurring. A more desirable ratio is from approximately 0.1 toapproximately 2% by weight. The polymerizable compound is polymerizedpreferably in the presence of a suitable initiator, such as aphotopolymerization initiator, under radiation of ultraviolet light.Suitable conditions for polymerization and a suitable type and asuitable amount of the initiator have been known by a skilled person inthe art and are disclosed in literatures. Examples of thephotopolymerization initiator suitable for radical polymerizationinclude Irgacure 651 (trade name), Irgacure 184 (trade name) andDarocure 1173 (trade name), all produced by Ciba Japan K.K. Thepolymerizable compound preferably contains a photopolymerizationinitiator in an amount of from approximately 0.1 to approximately 5% byweight, and particularly preferably contains a photopolymerizationinitiator in an amount of from approximately 1 to approximately 3% byweight.

Seventh, the preparation methods of the component compounds will beexplained. These compounds can be prepared by known methods. Thepreparation method will be exemplified below. The compound (1) isprepared by the method disclosed in JP H9-286742 A/1997. The compounds(3-1-1-1) and (3-2-1-1) are prepared by the method disclosed in JPH4-30382 B/1992. The compounds (4-5-1) and (4-8-1) are prepared by themethod disclosed in JP H2-233626 A/1990. The compounds (4-11-1) and(4-12-1) are prepared by the method disclosed in JP H10-251186 A/1998.The antioxidant is commercially available. The compound (6), wherein nis 1, is available, for example, from Sigma-Aldrich, Inc. The compound(6), wherein is 7, is prepared by the method disclosed in U.S. Pat. No.3,660,505.

The compounds for which preparation methods were not described above canbe prepared according to the methods described in Organic Syntheses(John Wiley & Sons, Inc.), Organic Reactions (John Wiley & Sons, Inc.),Comprehensive Organic Synthesis (Pergamon Press), New ExperimentalChemistry Course (Shin Jikken Kagaku Kouza) (Maruzen, Inc.), and soforth. The composition is prepared according to known methods using thecompounds thus obtained. For example, the component compounds are mixedand dissolved in each other by heating.

Last, use of the composition will be explained. Most of the compositionshave a minimum temperature of approximately −10° C. or less, a maximumtemperature of approximately 70° C. or more, and an optical anisotropyof approximately 0.07 to approximately 0.20. The device containing thecomposition has a large voltage holding ratio. The composition issuitable for an AM device. The composition is suitable especially for anAM device of a transmission type. The composition having an opticalanisotropy of approximately 0.08 to approximately 0.25 and furtherhaving an optical anisotropy of approximately 0.10 to approximately 0.30may be prepared by controlling ratios of the component compounds or bymixing other liquid crystal compounds. The composition can be used as acomposition having a nematic phase and as an optically activecomposition by adding an optically active compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for an AM device and a PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA, PSA and soforth. It is particularly desirable to use the composition for an AMdevice having a TN, OCB or IPS mode. These devices may be of areflection type, a transmission type or a semi-transmission type. It isdesirable to use the composition for a device of a transmission type. Itcan be used for an amorphous silicon-TFT device or a polycrystalsilicon-TFT device. The composition is also usable for a nematiccurvilinear aligned phase (NCAP) device prepared by microcapsulating thecomposition, and for a polymer dispersed (PD) device in which a threedimensional net-work polymer is formed in the composition.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention and specificexamples provided herein without departing from the spirit or scope ofthe invention. Thus, it is intended that the invention covers themodifications and variations of this invention that come within thescope of any claims and their equivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES

When a sample was a composition, it was measured as it was, and theobtained value is described here. When a sample was a compound, a samplefor measurement was prepared by mixing 15% by weight of the compound and85% by weight of mother liquid crystals. A value of characteristic ofthe compound was calculated by extrapolating from a value obtained bymeasurement. Namely: extrapolated value=(value measured forsample−0.85×value measured for mother liquid crystals)/0.15. When asmectic phase (or crystals) was separated out at this ratio at 25° C., aratio of the compound and mother liquid crystals was changed step bystep in the order of (10% by weight/90% by weight), (5% by weight/95% byweight), (1% by weight/99% by weight), respectively. Values for amaximum temperature, optical anisotropy, viscosity, and dielectricanisotropy of the compound were obtained by the extrapolation.

The composition of the mother liquid crystals is as shown below. All thepercentages for the composition are percentage by weight.

Measurement of the characteristics was carried out according to thefollowing methods. Most methods are described in the Standard ofElectric Industries Association of Japan, EIAJ ED-2521 A or those withsome modifications.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope and was heated at the rate of 1° C. per minute. A temperaturewas measured when a part of the sample began to change from a nematicphase into an isotropic liquid. A higher limit of a temperature range ofa nematic phase may be abbreviated to “a maximum temperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in a glass vial and then kept in a freezer attemperatures of 0° C., −10° C., −20° C., −30° C., and −40° C. for tendays, respectively, and a liquid crystal phase was observed. Forexample, when the sample remained in a nematic phase at −20° C. andchanged to crystals or a smectic phase at −30° C., Tc was expressed as≦−20° C. A lower limit of a temperature range of a nematic phase may beabbreviated to “a minimum temperature.”

Viscosity (η; measured at 20° C., mPa·s): A viscosity was measured bymeans of an E-type viscometer.

Rotation Viscosity (γ1; measured at 25° C.; mPa·s): Rotation viscositywas measured according to the method disclosed in M. Imai, et al.,Molecular Crystals and Liquid Crystals, vol. 259, p. 37 (1995). A samplewas placed in a device, in which a twist angle was 0°, and a distancebetween two glass substrates (cell gap) was 5 μm. The TN device wasapplied with a voltage in a range of from 16 V to 19.5 V stepwise by 0.5V. After a period of 0.2 second with no application of voltage, voltageapplication was repeated with only one rectangular wave (rectangularpulse of 0.2 second) and application of no voltage (2 seconds). A peakcurrent and a peak time of a transient current generated by the voltageapplication were measured. Rotation viscosity was obtained from themeasured values and the calculating equation (8) in the literature by M.Imai, et al., p. 40. As the dielectric anisotropy necessary for thecalculation, the value measured by the measuring method of dielectricanisotropy described below with the device for measuring the rotationviscosity was used.

Optical Anisotropy (Δn; refractive index anisotropy measured at 25° C.):Measurement was carried out with an Abbe refractometer mounting apolarizing plate on an ocular using a light at a wavelength of 589 nm.The surface of a main prism was rubbed in one direction, and then asample was dropped on the main prism. Refractive index (nil) wasmeasured when the direction of a polarized light was parallel to that ofthe rubbing. Refractive index (n⊥) was measured when the direction of apolarized light was perpendicular to that of the rubbing. A value ofoptical anisotropy was calculated from the equation:

Δn=n∥−n⊥.

Dielectric Anisotropy (Δ∈; measured at 25° C.): A sample was put in a TNdevice having a distance between two glass substrates (cell gap) of 9 μmand a twist angle of 80°. Sine waves (10 V, 1 kHz) were applied to thedevice and a dielectric constant (∈∥) in a major axis direction of aliquid crystal molecule was measured after 2 seconds. Sine waves (0.5 V,1 kHz) were applied to the device and a dielectric constant (∈⊥) in aminor axis direction of a liquid crystal molecule was measured after 2seconds. A value of a dielectric anisotropy was calculated from theequation:

Δ∈=∈∥=∈⊥.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with an LCD Evaluation System Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. A sample waspoured into a TN device of a normally white mode, in which a cell gapbetween two glass plates was about 0.45/Δn (μm), and a twist angle was80°. Voltage to be applied to the device (32 Hz, rectangular waves) wasstepwise increased by 0.02 volt starting from 0 V up to 10 V. During thestepwise increasing, the device was irradiated with light in aperpendicular direction, and an amount of the light passing through thedevice was measured. Voltage-transmission curve was prepared, in which amaximum amount of a light corresponded to 100% transmittance, a minimumamount of a light corresponded to 0% transmittance. Threshold voltage isa value at 90% transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement has a polyimide-alignment film and the cell gap betweentwo glass substrates is 5 μm. This device was sealed with adhesivepolymerized with ultraviolet ray after the sample is put into thedevice. The pulse voltage (60 microseconds at 5 V) was applied to the TNdevice for charging. A decreasing voltage was measured for 16.7milliseconds by a high-speed voltmeter. An area A between voltage curveand horizontal axis per unit cycle was obtained. An area B is an areawhen a voltage is not decreased. A voltage holding ratio is percentageof the area A relative to the area B.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement has a polyimide-alignment film and the cell gap betweentwo glass substrates is 5 μm. This device was sealed with adhesivepolymerized with ultraviolet ray after the sample is put into thedevice. The pulse voltage (60 microseconds at 5 V) was applied to the TNdevice for charging. A decreasing voltage was measured for 16.7milliseconds by a high-speed voltmeter. An area A between voltage curveand horizontal axis per unit cycle was obtained. An area B is an areawhen a voltage is not decreased. A voltage holding ratio is percentageof the area A relative to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): A voltage holdingratio was measured after irradiating with ultraviolet light to evaluatestability to ultraviolet light. A composition having large VHR-3 has alarge stability to ultraviolet light. A TN device used for measurementhas a polyimide-alignment film and the cell gap is 5 μm. A sample waspoured into the device, and then the device was irradiated with lightfor 20 minutes. The light source was a superhigh voltage mercury lampUSH-500D (produced by Ushio, Inc.), and the distance between the deviceand the light source is 20 cm. In measurement of VHR-3, a decreasingvoltage is measured for 16.7 milliseconds. VHR-3 is desirably 90% ormore, and more desirably 95% or more.

Voltage Holding Ratio (VHR-4; measured at 25° C.; %): A voltage holdingratio was measured after heating an TN device having a sample pouredtherein in a constant-temperature bath at 80° C. for 500 hours toevaluate stability to heat. A composition having large VHR-4 has a largestability to heat. In measurement of VHR-4, a decreasing voltage ismeasured for 16.7 milliseconds.

Response Time (τ; measured at 25° C.; millisecond): Measurement wascarried out with an LCD Evaluation System Model LCD-5100 made by OtsukaElectronics Co., Ltd. Light source is a halogen lamp. Low-pass filterwas set at 5 kHz. A sample was poured into a TN device of a normallywhite mode, in which a cell gap between two glass plates was 5.0 μm, anda twist angle was 80°. Rectangle waves (60 Hz, 5 V, 0.5 seconds) wereimpressed to the device. During impressing, the device was irradiatedwith light in a perpendicular direction, and an amount of the lightpassing through the device was measured. A maximum amount of a lightcorresponds to 100% transmittance, and a minimum amount of a lightcorresponds to 0% transmission. Rise time (τr: rise time; milliseconds)is a period of time required for the change in transmittance from 90% to10%. Fall time (τf: fall time; milliseconds) is a period of timerequired for the change in transmittance from 10% to 90%. Response timeis a sum of the rise time and the fall time thus obtained.

Specific Resistance (ρ; measured at 25° C.; Ωcm): 1.0 mL of a sample wascharged in a vessel equipped with electrodes. A direct current voltageof 10 V was impressed to the vessel, and after lapsing 10 second fromthe impress of voltage, the direct electric current was measured. Thespecific resistance was calculated by the equation: (specificresistance)={(voltage)×(electric capacity of vessel)}/{(directcurrent)×(dielectric constant of vacuum)}.

Gas Chromatographic Analysis: A Gas Chromatograph Model GC-14B made byShimadzu was used for measurement. The carrier gas was helium (2milliliters per minute). An evaporator and a detector (FID) were set upat 280° C. and 300° C., respectively. Capillary column DB-1 (length 30meters, bore 0.32 millimeters, film thickness 0.25 micrometers,dimethylpolysiloxane as stationary phase, no polarity) made by AgilentTechnologies, Inc. was used for the separation of the componentcompound. After the column had been kept at 200° C. for 2 minutes, itwas further heated to 280° C. at the rate of 5° C. per minute. A samplewas prepared in an acetone solution (0.1% by weight), and 1 microliterof the solution was injected into the evaporator. The recorder used wasa Chromatopac Model C-R5A made by Shimadzu or its equivalent. Gaschromatogram obtained showed a retention time of a peak and a peak areacorresponding to the component compound.

Solvents for diluting the sample may also be chloroform, hexane, and soforth. The following capillary columns may also be used for theseparation of the component compound: HP-1 made by Agilent TechnologiesInc. (length 30 meters, bore 0.32 millimeters, film thickness 0.25micrometers), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeters, film thickness 0.25 micrometers), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeters, filmthickness 0.25 micrometers). In order to prevent compound peaks fromoverlapping, a capillary column CBP1-M50-025 (length 50 meters, bore0.25 millimeters, film thickness 0.25 micrometers) made by ShimadzuCorporation may be used.

The content ratios of the liquid crystal compounds contained in thecomposition can also be calculated in the following manner. A liquidcrystal compound can be detected by gas chromatography. An area ratio ofpeaks on a gas chromatogram corresponds to a content ratio (molarnumber) of liquid crystal compounds. In the case where theaforementioned capillary columns are used, correction coefficients ofthe liquid crystal compounds can be regarded as 1. Accordingly, thecontent ratio (% by weight) of liquid crystal compounds is calculatedfrom the area ratio of peaks.

The invention will be explained in detail by way of Examples. Theinvention is not limited by the Examples described below. The compoundsdescribed in the Comparative Examples and the Examples are expressed bythe symbols according to the definition in Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. The parenthesized numbernext to the symbolized compounds in the Examples corresponds to thenumber of the desirable compound. The symbol (−) means other liquidcrystal compound. A ratio (percentage) of a liquid crystal compound ispercentage by weight (% by weight) based on the total weight of liquidcrystal compounds, and the liquid crystal compositions further containimpurities. Last, the characteristics of the composition are summarized.

TABLE 3 Method of Description of Compound using Symbols R—(A₁)—Z₁— . . .—Z_(n)—(A_(n))—R′ (1) Left Terminal Group R— Symbol C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V—C_(n)H_(2n+1)═CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn- (2) Right Terminal Group —R′ Symbol —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn—C_(n)H_(2n)—CH═CH₂ -nV —CH═CF₂ —VFF —F —F —Cl —CL —OCF₃ —OCF3 (3)Bonding Group —Zn— Symbol —C₂H₄— 2 —COO— E —CH═CH— V —C≡C— T —CF₂O— X(4) Ring structure -An- Symbol

H

B

B(F)

B(2F)

B(F,F)

B(2F,5F)

Py

G

Hd

B(2CH3) (5) Example of Description Example 1 V2-BB-2V

Example 2 3-HB-CL

Example 3 5-HBB(F)B-3

Example 4 3-BB(F)B(F,F)XB(F,F)-F

Comparative Example 1

A composition corresponding to Example 2 of JP H10-81881 A/1998 wasselected. The basis is that the composition contains the compound (1),the compound (3-1-1-1) and the compound (4), and has the minimumviscosity (η). The components and characteristics of the compositionwere as follows.

V2-BB—2V (1) 15% 3-HBTB-1 (-) 7% 3-HBTB(2CH3)-1 (-) 6%3-HdB(F,F)TB(2CH3)-1 (-) 12% 3-HBTB(F,F)—F (-) 13% 3-HdB(F,F)TB(F)—F (-)13% 3-B(F)BTB(F)—F (-) 10% 3-B(F)BTB(F,F)—F (-) 8% V2-HH-3 (3-1-1-1) 8%V2-HHB(F)—F (4) 8% NI = 102.7° C.; Δn = 0.229; Vth = 2.08 V; η = 21.3mPa · s

Example 1

The composition of Example I has a small viscosity as compared toComparative Example 1.

V2-BB—2V (1) 9% 3-BB(F)B(F,F)XB(F,F)—F (2-1-1) 4% 4-BB(F)B(F,F)XB(F,F)—F(2-1-1) 5% V—HH-3 (3-1-1-1) 47% 2-BB(F)B-3 (3-2-3-1) 6% 1-BB(F)B—2V(3-2-3-1) 5% 2-BB(F)B—2V (3-2-3-1) 8% 3-BB(F)B—2V (3-2-3-1) 13%3-BB(F,F)XB(F,F)—F (4-11-1) 3% NI = 74.0° C.; Tc ≦ −20° C.; Δn = 0.132;Δε = 2.4; Vth = 2.68 V; η = 11.9 mPa · s; γ1 = 37.2 mPa · s; τ = 3.4 ms;VHR-1 = 99.3%; VHR-2 = 98.4%; VHR-3 = 98.2%

Example 2

The composition of Example 2 has a small viscosity as compared toComparative Example 1.

V2-BB—2V (1) 10% 3-BB(F)B(F,F)XB(F,F)—F (2-1-1) 3%4-BB(F)B(F,F)XB(F,F)—F (2-1-1) 7% V—HH-3 (3-1-1-1) 44% 1-BB(F)B—2V(3-2-3-1) 8% 2-BB(F)B—2V (3-2-3-1) 8% V—HHB-1 (3-2-1-1) 4% 3-HHB—CL(4-4-1) 3% 3-HHXB(F,F)—F (4-6-1) 5% 3-HBB—F (4-7-1) 3%3-BB(F,F)XB(F,F)—F (4-11-1) 5% NI = 72.9° C.; Tc ≦ −20° C.; Δn = 0.120;Δε = 3.5; Vth = 2.30 V; η = 14.2 mPa · s; γ1 = 42.5 mPa · s; τ = 4.1 ms;VHR-1 = 99.4%; VHR-2 = 98.5%; VHR-3 = 98.3%

Example 3

The composition of Example 3 has a small viscosity as compared toComparative Example 1.

V2-BB—2V (1) 5% 3-BB(F)B(F,F)XB(F,F)—F (2-1-1) 4% 4-BB(F)B(F,F)XB(F,F)—F(2-1-1) 4% 5-BB(F)B(F,F)XB(F,F)—F (2-1-1) 3% 3-BB(F)B(F,F)XB(F)—OCF3(2-3-1) 3% V—HH-3 (3-1-1-1) 45% 1V—HH-3 (3-1-1-1) 10% 1-BB(F)B—2V(3-2-3-1) 8% 3-HHXB(F,F)—F (4-6-1) 15% 3-HHBB(F,F)—F (-) 3% NI = 75.4°C.; Tc ≦ −20° C.; Δn = 0.100; Δε = 3.2; Vth = 2.30 V; η = 16.0 mPa · s;γ1 = 46.3 mPa · s; τ = 4.8 ms; VHR-1 = 99.1%; VHR-2 = 98.2%; VHR-3 =98.0%

Example 4

V2-BB—2V (1) 7% 3-BB(F)B(F,F)XB(F,F)—F (2-1-1) 3%3-BB(F,F)B(F,F)XB(F,F)—F (2-2-1) 7% V—HH-3 (3-1-1-1) 40% 1V—HH-3(3-1-1-1) 5% 1-BB(F)B—2V (3-2-3-1) 7% 2-BB(F)B—2V (3-2-3-1) 8%3-BB(F)B—2V (3-2-3-1) 6% 5-HBB(F)B-2 (3-3-3-1) 5% 3-BB(F)B(F,F)—F(4-9-1) 7% 3-BB(F,F)XB(F,F)—F (4-11-1) 5% NI = 74.2° C.; Tc ≦ −20° C.;Δn = 0.143; Δε = 4.2; Vth = 2.43 V; η = 18.2 mPa · s; γ1 = 51.0 mPa · s;τ = 5.4 ms; VHR-1 = 99.3%; VHR-2 = 98.4%; VHR-3 = 98.2%

Example 5

V2-BB—2V (1) 6% 3-BB(F)B(F,F)XB(F,F)—F (2-1-1) 3% 4-BB(F)B(F,F)XB(F,F)—F(2-1-1) 5% 3-BBB(F,F)XB(F,F)—F (2-8) 4% V—HH-3 (3-1-1-1) 48% V—HHB-1(3-2-1-1) 4% V2-HHB-1 (3-2-1-1) 4% 1-BB(F)B—2V (3-2-3-1) 5% 3-HHB—CL(4-4-1) 3% 3-HHXB(F,F)—F (4-6-1) 4% 3-HBB(F,F)—F (4-8-1) 5%3-BB(F,F)XB(F,F)—F (4-11-1) 3% 3-HHBB(F,F)—F (-) 3% 3-HHEBH-3 (-) 3% NI= 80.8° C.; Tc ≦ −20° C.; Δn = 0.104; Δε = 3.0; Vth = 2.46 V; η = 18.0mPa · s; γ1 = 52.2 mPa · s; τ = 5.2 ms; VHR-1 = 99.3%; VHR-2 = 98.3%;VHR-3 = 98.2%

Example 6

V2-BB—2V (1) 13% 4-BB(F)B(F,F)XB(F,F)—F (2-1-1) 6% 3-BBB(F,F)XB(F,F)—F(2-8) 4% 1V—HH-3 (3-1-1-1) 7% V—HH-5 (3-1-1-1) 20% 3-HH—VFF (3-1-1-2)15% V2-HHB-1 (3-2-1-1) 5% V2-BB(F)B-1 (3-2-3-1) 5% 2-BB(F)B-3 (3-2-3-1)5% 3-HHB(F,F)—F (4-5-1) 3% 3-HHXB(F,F)—F (4-6-1) 5% 3-PyBB—F (4-10-1) 4%4-PyBB—F (4-10-1) 4% 5-PyBB—F (4-10-1) 4% NI = 81.4° C.; Tc ≦ −20° C.;Δn = 0.131; Δε = 4.0; Vth = 2.24 V; η = 18.5 mPa · s; γ1 = 53.8 mPa · s;τ = 5.4 ms; VHR-1 = 99.0%; VHR-2 = 98.2%; VHR-3 = 98.0%

Example 7

V2-BB—2V (1) 5% 4-BB(F)B(F,F)XB(F,F)—F (2-1-1) 7% 3-BBB(F,F)XB(F)—CL(2-7) 3% V—HH-3 (3-1-1-1) 54% 1V—HH-3 (3-1-1-1) 3% 1-BB(F)B—2V (3-2-3-1)8% 2-BB(F)B—2V (3-2-3-1) 6% 3-BB(F,F)XB(F)—OCF3 (4-12-1) 5% 5-GHB(F,F)—F(4-19) 3% 3-HHBB(F,F)—F (-) 3% 4-HHBB(F,F)—F (-) 3% NI = 72.6° C.; Tc ≦−20° C.; Δn = 0.108; Δε = 2.3; Vth = 2.40 V; η = 15.0 mPa · s; γ1 = 45.2mPa · s; τ = 4.3 ms; VHR-1 = 99.4%; VHR-2 = 98.4%; VHR-3 = 98.2%

Example 8

V2-BB—2V (1) 6% 3-BB(F)B(F,F)XB(F)—OCF3 (2-3-1) 5% V—HH-3 (3-1-1-1) 46%3-HHB-1 (3-2-1-1) 4% V2-BB(F)B-1 (3-2-3-1) 5% V2-BB(F)B-2 (3-2-3-1) 4%1-BB(F)B—2V (3-2-3-1) 5% 2-BB(F)B—2V (3-2-3-1) 4% 3-HB—CL (4-1-1) 4%3-HHXB(F,F)—F (4-6-1) 8% 5-PyB(F)XB(F,F)—F (4-21) 3% 5-PyB(F,F)XB(F,F)—F(4-22) 3% 1O1-HBBH-5 (-) 3% NI = 74.3° C.; Tc ≦ −20° C.; Δn = 0.114; Δε= 3.2; Vth = 2.33 V; η = 13.1 mPa · s; γ1 = 41.9 mPa · s; τ = 3.8 ms;VHR-1 = 99.0%; VHR-2 = 98.0%; VHR-3 = 97.8%

Example 9

V2-BB—2V (1) 10% 3-BB(F)B(F,F)XB(F,F)—F (2-1-1) 5% 2-HH-3 (3-1-1-1) 24%3-HH-4 (3-1-1-1) 10% V—HHB-1 (3-2-1-1) 3% 2-BB(F)B-3 (3-2-3-1) 10%1-BB(F)B—2V (3-2-3-1) 8% 3-HB—CL (4-1-1) 8% 3-HHXB(F)—F (4-13) 6%4-BB(F,F)XB(F)—F (4-15) 6% 3-GHXB(F,F)—F (4-20) 5% 3-HHEBH-3 (-) 5% NI =72.2° C.; Tc ≦ −20° C.; Δn = 0.141; Δε = 2.9; Vth = 2.49 V; η = 19.6 mPa· s; γ1 = 57.5 mPa · s; τ = 6.2 ms; VHR-1 = 99.0%; VHR-2 = 97.8%; VHR-3= 97.7%

Example 10

V2-BB—2V (1) 5% 3-BB(F)B(F,F)XB(F,F)—F (2-1-1) 5% 4-BB(F)B(F,F)XB(F,F)—F(2-1-1) 5% V—HH-3 (3-1-1-1) 49% V2-BB(F)B-1 (3-2-3-1) 6% 1-BB(F)B—2V(3-2-3-1) 6% 2-BB(F)B-3 (3-2-3-1) 3% 5-HBB(F)B-2 (3-3-3-1) 3%5-HBB(F)B-3 (3-3-3-1) 3% 3-HHXB(F,F)—F (4-6-1) 3% 3-HHEB(F,F)—F (4-16)3% 3-HBEB(F,F)—F (4-17) 3% 3-HGB(F,F)—F (4-18) 3% 1O1-HBBH-5 (-) 3% NI =85.9° C.; Tc ≦ −20° C.; Δn = 0.120; Δε = 2.6; Vth = 2.65 V; η = 19.7 mPa· s; γ1 = 57.1 mPa · s; τ = 5.7 ms; VHR-1 = 99.3%; VHR-2 = 98.5%; VHR-3= 98.2%

Example 11

V2-BB—2V (1) 5% 3-BB(F)B(F,F)XB(F)—F (2-4) 4% 4-BB(F)B(F,F)XB—OCF3 (2-5)4% 3-BB(F,F)B(F,F)XB(F)—OCF3 (2-6) 4% V—HH-3 (3-1-1-1) 30% 3-HH—VFF(3-1-1-2) 15% 7-HB-1 (3-1-2-1) 3% 3-HB—O2 (3-1-2-1) 3% 3-HBB-2 (3-2-2-1)7% 1-BB(F)B—2V (3-2-3-1) 5% 2-BB(F)B-3 (3-2-3-1) 5% 1V2-BB—F (4-2-1) 3%1V2-BB—CL (4-3-1) 3% 3-HHXB(F)—OCF3 (4-14) 3% 3-HHBB(F,F)—F (-) 3%3-HHEBH-3 (-) 3% NI = 70.4° C.; Tc ≦ −20° C.; Δn = 0.116; Δε = 3.9; Vth= 2.36 V; η = 15.1 mPa · s; γ1 = 48.4 mPa · s; τ = 5.0 ms; VHR-1 =99.3%; VHR-2 = 98.1%; VHR-3 = 98.0%

Example 12

V2-BB—2V (1) 5% 3-BB(F)B(F,F)XB(F,F)—F (2-1-1) 3% 4-BB(F)B(F,F)XB(F,F)—F(2-1-1) 7% V—HH-3 (3-1-1-1) 45% 1V—HH-3 (3-1-1-1) 6% 1-BB(F)B—2V(3-2-3-1) 8% 2-BB(F)B—2V (3-2-3-1) 6% 2-BBB(2F)-4 (3-2-4-1) 4% 5-HBBH-2(3-3-1-1) 4% 5-HBB(2F)H-3 (3-3-2-1) 3% 5-GHB(F,F)—F (4-19) 3%3-HHBB(F,F)—F (-) 3% 4-HHBB(F,F)—F (-) 3% NI = 90.2° C.; Tc ≦ −20° C.;Δn = 0.130; Δε = 2.2; Vth = 2.70 V; η = 19.9 mPa · s; γ1 = 57.0 mPa · s;τ = 6.3 ms; VHR-1 = 99.3%; VHR-2 = 98.3%; VHR-3 = 98.3%

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the disclosure has beenmade only by way of example, and that numerous changes in the conditionsand order of steps can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention.

1. A liquid crystal composition having a nematic phase comprising twocomponents, wherein the first component is a compound represented byformula (1), and the second component is at least one compound selectedfrom the group consisting of compounds represented by formula (2):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; X¹, X², X³and X⁴ are each independently hydrogen or fluorine; and Y¹ is fluorine,chlorine or trifluoromethoxy.
 2. The liquid crystal composition of claim1, wherein the second component is at least one compound selected fromthe group consisting of compounds represented by formulas (2-1) to(2-3):

wherein R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons.
 3. The liquid crystal composition of claim 2, wherein thesecond component is at least one compound selected from the groupconsisting of compounds represented by formula (2-1).
 4. The liquidcrystal composition of claim 1, wherein a content ratio of the firstcomponent is from approximately 5% by weight to approximately 30% byweight, and a content ratio of the second component is fromapproximately 5% by weight to approximately 30% by weight, based on thetotal weight of the liquid crystal composition.
 5. The liquid crystalcomposition of claim 1, wherein the composition further comprises athird component of at least one compound selected from the groupconsisting of compounds represented by formulas (3-1) to (3-3):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; and ring B, ring C, ring D, ring E, ring F and ring G are eachindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneor 3-fluoro-1,4-phenylene.
 6. The liquid crystal composition of claim 5,wherein the third component is at least one compound selected from thegroup consisting of compounds represented by formulas (3-1-1), (3-1-2),(3-2-1) to (3-2-4) and (3-3-1) to (3-3-3):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; and R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to12 carbons.
 7. The liquid crystal composition of claim 6, wherein thethird component is at least one compound selected from the groupconsisting of compounds represented by formula (3-1-1).
 8. The liquidcrystal composition of claim 6, wherein the third component is at leastone compound selected from the group consisting of compounds representedby formula (3-2-1).
 9. The liquid crystal composition of claim 6,wherein the third component is at least one compound selected from thegroup consisting of compounds represented by formula (3-2-3).
 10. Theliquid crystal composition of claim 6, wherein the third component is atleast one compound selected from the group consisting of compoundsrepresented by formula (3-3-3).
 11. The liquid crystal composition ofclaim 5, wherein a content ratio of the third component is fromapproximately 40% by weight to approximately 95% by weight based on thetotal weight of the liquid crystal composition.
 12. The liquid crystalcomposition of claims 1, wherein the composition further comprises afourth component of at least one compound selected from the groupconsisting of compounds represented by formula (4):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; ring A isindependently 1,4-cyclohexylene, 1,3-dioxan-2,5-diyl, 1,4-phenylene,3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene or 2,5-pirimidine; Z¹is independently a single bond, ethylene, carbonyloxy ordifluoromethyleneoxy; X¹ and X² are each independently hydrogen orfluorine; Y¹ is fluorine, chlorine or trifluoromethoxy; and n is 1 or 2.13. The liquid crystal composition of claim 12, wherein the fourthcomponent is at least one compound selected from the group consisting ofcompounds represented by formulas (4-1) to (4-12):

wherein R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons.
 14. The liquid crystal composition of claim 13, wherein thefourth component is at least one compound selected from the groupconsisting of compounds represented by formula (4-6).
 15. The liquidcrystal composition of claim 13, wherein the fourth component is atleast one compound selected from the group consisting of compoundsrepresented by formula (4-8).
 16. The liquid crystal composition ofclaim 13, wherein the fourth component is at least one compound selectedfrom the group consisting of compounds represented by formula (4-10).17. The liquid crystal composition of claim 13, wherein the fourthcomponent is at least one compound selected from the group consisting ofcompounds represented by formula (4-11).
 18. The liquid crystalcomposition of claim 13, wherein the fourth component is a mixture of atleast one compound selected from the group consisting of compoundsrepresented by formula (4-6) and at least one compound selected from thegroup consisting of compounds represented by formula (4-11).
 19. Theliquid crystal composition of claim 12, wherein a content ratio of thefourth component is from approximately 5% by weight to approximately 35%by weight based on the total weight of the liquid crystal composition.20. The liquid crystal composition of claim 1, wherein the compositionhas a maximum temperature of a nematic phase of approximately 70° C. ormore, an optical anisotropy (25° C.) at a wavelength of 589 nm ofapproximately 0.08 or more, and a dielectric anisotropy (25° C.) at afrequency of 1 kHz of approximately 2 or more.
 21. A liquid crystaldisplay device that includes the liquid crystal composition of claim 1.22. The liquid crystal display device of claim 21, wherein the liquidcrystal display device has an operation mode selected from the groupconsisting of a TN mode, an OCB mode, an IPS mode and a PSA mode, andhas a driving mode of an active matrix mode.